1 Ostium secundum atrial septal defect
The ostium secundum atrial septal defect is the most common type of atrial septal defect, and comprises 6–10% of all congenital heart diseases.
Most individuals with an uncorrected secundum ASD do not have significant symptoms through early adulthood. More than 70 percent develop symptoms by about 40 years of age. Symptoms are typically decreased exercise tolerance, easy fatigueability, palpitations, and syncope.
2 Patent foramen ovale
A patent foramen ovale (PFO) is a small channel that has some hemodynamic consequence; it is a remnant of the fetal foramen ovale. Clinically it is linked to decompression sickness, paradoxical embolism and migraine. On echocardiography, there may not be any shunting of blood noted except when the patient coughs.
There is debate within the neurology and cardiology communities about the role of a PFO in cryptogenic (i.e. of unknown cause) neurologic events such as strokes and transient ischemia attacks (TIAs) without any other potential cause.
3 Ostium primum atrial septal defect
A defect in the ostium primum is occasionally classified as an atrial septal defect, but it is more commonly classified as an atrioventricular septal defect. Ostium primum defects are less common than ostium secundum defects.